Advice For BIL And Cheating SIL

Hi, I am after some advice for my BIL who found out this week that his wife has been having an affair with a work colleague (they all work at the same company) he has told her it is over. They have a 3 year old. They live in a house that he brought before they were together and the mortgage is still is in his name but obviously that was before nearly 3 year of marriage (nearly 10 year together) i think he thought that would be enough to protect him if they split but some quick internet reading indicates that this would not be the case as she would be the main parent of DN. So can anybody help me with some questions or point me in the right direction. If she gets the house because of being the main parent with responsibility for DN can she make him leave the house?If he moves out how much would he have to pay? He understands and is more than happy to pay maintenance and has been on the CSA website for info, but would he have to pay more than this? i.e. what happens to the mortgage, utility, car nursery fees etc.Many thanks in advance.

I think your BIL should speak to CAB / a family lawyer. He can get generic info online but probably wants specifics, e.g. the business about the house and who is the resident parent. If both parents work and the child is 3 presumably there's other childcare in place. I think it best he remains at home til getting professional advice.